Knee pillows having a variety of shapes and structures have been proposed for cushioning the knees of the user. Some such pillows are intended to be positioned between the user's knees (e.g., while the user sleeps on his or her side) to prevent one knee from exerting painful or uncomfortable pressure on the other. Such knee pressure may be especially painful or uncomfortable to some users, for example some persons having an arthritic condition in their lower extremities.
Some knee pillows are designed to be strapped to one or both legs of the user by straps, in a position for separating and cushioning the user's knees (e.g., while the user sleeps on his or her side). For example, U.S. Pat. No. 4,177,806, issued Dec. 11, 1979, discloses a knee pillow including a cloth-covered resilient pad with one or two pairs of straps to be fastened to at least one leg of a user; U.S. Pat. No. 4,736,477, issued Apr. 12, 1988, discloses a knee pillow including a plastic-covered (or cloth-covered), deformable and resilient core with straps to be fastened to a user's leg; U.S. Pat. No. 6,145,508, issued Nov. 14, 2000, discloses a knee pillow including three cloth-covered cushions (two made of foam, gel, down, or other “first” cushion material; the other made of batting or other material different than the first cushion material) and straps having releasable fasteners (e.g., hook-and-loop fasteners) to be fastened to a user's leg; U.S. Pat. No. 4,706,302, issued Nov. 17, 1987, discloses a knee pad having a Y-shaped strap (with hook and loop fasteners to be fastened to a user's leg) and a pad that can include padding, liquid gel, or other cushioning material; and U.S. Pat. No. 6,807,697, issued Oct. 26, 2004, discloses a knee pillow with three straps having hook and loop fasteners, and a covered pad filled with resilient material (e.g., a pad filled with polyurethane foam and covered by a washable cover). Similarly, U.S. Pat. No. 5,560,041, issued Oct. 1, 1996, discloses an equestrian knee grip-pad having two straps with hook and loop fasteners and a pad having a high-friction outer surface and low-friction inner surface. However, the pillows and pads disclosed in the cited references are bulky and typically, undesirably heavy, because they are filled with resilient or other cushioning material.
U.S. Pat. No. 4,889,109, issued Dec. 26, 1989, discloses a large knee pillow having complicated shape and a strap for surrounding both legs of the user. The pillow has a central projecting portion to be placed between the user's knees to separate the knees while the legs of a user in a supine position rest on end portions of the pillow. An inflatable embodiment of this pillow (shown in FIG. 7 of U.S. Pat. No. 4,889,109) is also undesirably large with an undesirably complicated shape and design (including a central projecting portion to be placed between the knees of a supine user while the user's legs rest on end portions of the pillow, and internal structural members for holding the pillow in its intended inflated shape), and is unsuitable for use by a user lying on his or her side.
U.S. Pat. No. 5,613,941, issued Mar. 25, 1997, and U.S. Pat. No. 5,451,201, issued Sep. 19, 1995, disclose knee supports (braces) for restricting movement of the knee joint. One such support is filled with resilient material and has two straps to be fastened to a user's leg; another has two such straps, a resilient body, and an inflatable bladder attached to the body. The bladder has a generally circular or oval central portion for encircling the user's patella and two elongated stay portions for lateral support. These knee supports are heavy and bulky, and unsuitable for use as knee pillows.
There is a need for an inflatable knee pillow which is lightweight, inexpensively manufacturable, comfortable to wear (over clothing or against bare skin), provides good knee cushioning (e.g., to a user lying on his or her side), and is easily inflatable (e.g., without use of an air pump), and also has a thin profile when not inflated and can be folded into a small package when not inflated.